On reproducing a disk record by a record player, it is required to place the record on a turntable in a concentric manner relative to the rotational center of the turntable because, if otherwise, a wow occurs due to an off-center rotation of the record whereby the reproducing characteristic of the record is deteriorated.
To this end, in general, the turntable has a center spindle provided thereon, and the record is placed on the turntable so that a center hole of the record engages the center spindle of the turntable. The diameters of the spindle and the center hole are standardized.
However, in the Industrial Standards, the center of the center hole is allowed to be distant from the center of the groove spiral within 0.2 mm. Also, concerning LP record for example, the diameter of the center hole is allowed to vary from 7.24 to 7.33 mm while the diameter of the center spindle is allowed to vary from 7.05 to 7.15 mm. Thus, it will be noted that a clearance between the center spindle and the center hole always occurs in placing the record on the turntable. It will be also noted that the clearance will be much greater in accordance with the combination of the record and the record player used.
Thus, it will be understood that it is difficult to place the record on the turntable in a concentric manner relative to the rotational center of the turntable only by engaging the center hole of the record with the center spindle of the turntable. In a prior art, it is usual to place the record on the turntable in an eccentric manner, and the degree of eccentricity of the record relative to the rotational center of the turntable disadvantageously depends on how the record is placed on the turntable.